It has been known for a number of years to utilize focused energy in the form of heat or electricity to burn or scar skin and underlying tissue in connection with the treatment of various ailments and disease. The practice, known as cauterization, has been particularly useful for the removal of abnormal skin growths. One drawback to the practice has been the generation of foul-smelling materials at the site resulting from the burning of the tissue. Fortunately, the volume of these materials was typically relatively low due to the type of ailments treated by the process. However, where electrocautery is used to seal blood vessels in connection with invasive surgery, the volume of materials generated is substantially increased.
Since the 1970's, lasers have been used in operating rooms to treat a wide variety of ailments. As in the traditional practice of cauterization, the laser was used to burn or sear tissue. However, because the laser was used in larger scale invasive surgery, the amount of materials generated at the site was substantially larger than that from traditional cauterization, with resulting problems related to the volume of the foul-smelling materials and the effect on operating room personnel.
The gas-generation problem has become more prevalent because in a number of surgical applications, lasers have an advantage over conventional scalpel cutting tools in that the laser is a more precise instrument, resulting in less trauma to adjacent tissue. Also, because the heat generated by the laser cauterizes the tissue as it is being cut, there is less blood loss and the healing process is speeded along.
In operation, the laser scalpel performs its cutting function by burning a narrow width of tissue. This process vaporizes moisture in the tissue and creates a smoke plume consisting primarily of water vapor, but which also includes small quantities of potentially hazardous and toxic gases, odor-causing gases, particulate matter of 1 micron or less, and bacteria and viruses.
This smoke generated by the laser scalpel, otherwise known as the laser plume, creates a variety of problems for the surgical operating team. The laser plume obscures the view of the surgeon during cutting. Further, the plume eventually deposits a coating on the mirrors used for viewing the cutting site. The operating room personnel also risk contracting infection by inhaling bacteria and virus from the tissue vaporized by the laser which are carried in the plume. The materials generated by the laser scalpel and carried in the laser plume tend to cause headaches and nausea, and more rarely nosebleeds and vomiting, which in certain instances have forced the operation to be terminated due to the sickness of the personnel. Finally, it has recently been determined that low levels of mutagenic and carcinogenic agents such as cyanide, formaldehyde and benzene are carried along in the plume.
The volume of the generated laser plume is a function of the power of the laser scalpel. As higher powered lasers are used, increasing amounts of laser plume are generated, consequently increasing the risk and discomfort to the operating team. The major lasers used in the medical and surgical fields utilize the lasing materials Neodymium-Yttrium Aluminum Garnet (Nd:YAG), Carbon Dioxide and Argon.
Early attempts to address the problem of removing the laser plume involved the use of vacuum devices fitted with an activated charcoal filter. These early devices removed the laser plume smoke from the cutting site and improved the surgeon's view of the site. However, the vacuum device could not remove all of the plume generated by high energy laser scalpels. Also, the moisture in the plume would tend to deactivate the charcoal over a period of time. Further, the charcoal filter had little or no effect on reducing the odor.
To meet the new requirements caused by the use of higher powered lasers, LASE Inc., a subsidiary of U.S. Medical Corporation, Cincinnati, Ohio, developed a smoke evacuation system incorporating an activated charcoal filter, a moisture filter before the charcoal filter to prevent deactivation of the charcoal filter, a high efficiency particle absorbing filter for capturing particles as small as 0.12 micron, a larger diameter hose to capture the increased volume of laser plume generated, and a deodorizing cartridge to mask the odor created by the plume. One type of evacuator unit used in laser surgery was the Lase System II, from U.S. Medical Corporation, and discussed in U.S. Pat. No. 4,963,134 which is incorporated herein by reference.
In the middle 1980's, clinical studies were conducted which determined that amounts of mutagenic and carcinogenic agents such as cyanide, formaldehyde and benzene, and also traces of compounds such as acetone, isopropanol, cyclohexane, and toluene, are produced during the laser surgery operation. Studies also recently determined that bacteria and viruses in the tissue subjected to laser were carried in the active state in the plume. Smoke evacuation systems employing only activated carbon and a particulate filter are unable to remove the mutagenic agents, bacteria and virus species, and the odor causing species from the plume. Rather, these systems were only able to partially mask the odor causing species in the plume.